1. Field of the Invention
The present invention generally relates to mat members including inorganic fibers. More specifically, the present invention relates to a mat member used for an exhaust gas treating apparatus and a muffler apparatus of an automobile or the like.
2. Description of the Related Art
The number of automobiles is drastically increasing in this century. In proportion to the increase of the automobiles, the amount of exhaust gas discharged from internal combustion engines of the automobiles is drastically increasing. Particularly, various materials contained in exhaust gas of diesel engines may cause air pollution. Accordingly, this seriously influences the worldwide environment.
Under such a circumstance, various exhaust gas treating apparatuses have been suggested and utilized. In a normal exhaust gas treating apparatus, a cylinder-shaped member (casing) is provided at an exhaust pipe connected to a gas manifold of an engine. An exhaust gas treating part is provided in the cylinder-shaped member (casing). The exhaust gas treating part has opening parts for entry and exit of the exhaust gas. A large number of minute pores are provided inside the exhaust gas treating part. A catalyst carrier or an exhaust gas filter such as a diesel particulate filter (DPF) is used as an example of the exhaust gas treating part. In a case of, for example, the DPF, as the exhaust gas passes from the entry opening of the exhaust gas treating part to the exit opening of the exhaust gas treating part in order to be discharged, particles are trapped on walls of the peripheries of the pores in order to be eliminated from the exhaust gas.
It is normal practice to provide a holding seal member between the above-mentioned exhaust gas treating part and the casing. The holding seal member is configured to prevent breakage caused by contact of the exhaust gas treating part and the casing during driving of the automobile. In addition, the holding seal member is used for preventing the exhaust gas from leaking from a gap between the exhaust gas treating part and the casing. Furthermore, the holding seal member is configured to prevent the exhaust gas treating part from dropping off due to exhaust gas pressure. In addition, it is required to hold the temperature of the exhaust gas treating part high in order to maintain reactivity. Furthermore, a thermal insulation property is required for the holding seal member. A mat member including inorganic fibers such as an alumina group fiber can be used as a member satisfying these conditions.
The mat member is wound around (with respect to) at least a part of the external circumferential surface except the openings of the exhaust gas treating part. The mat member, fixed to the exhaust gas treating part in a body by taping or the like, functions as the holding seal member. After that, this united body is press fitted inside the casing so that the exhaust gas treating apparatus is formed.